KR20180042939A - Liquefied Gas Regasification System and Operation Method - Google Patents

Abstract

The present invention relates to a liquefied gas regasification system and an operation method thereof and, more specifically, relates to the liquefied gas regasification system smoothly discharging evaporated gas generated in a high-pressure pump to supply liquefied gas to be regasified to an evaporator to maintain a minimum operational level of the high-pressure pump; and an operation method thereof. According to the present invention, the system comprises: a high-pressure pump to compress liquefied gas supplied from a liquefied gas storage tank at high pressure; a knock-out drum receiving the evaporator gas generated from the high-pressure pump to allow the high pressure pump to maintain the minimum operational level; a gas discharge line to discharge gas from the knock-out drum; and a liquid discharge line to discharge liquid from the knock-out drum. Accordingly, the gas discharged through the gas discharge line is supplied to a gas consumer including the liquefied gas storage tank or a fuel supply system; and the liquid discharged through the liquid discharge line is supplied to a liquid consumer including a lower part of the liquefied gas storage tank.

Description

Technical Field [0001] The present invention relates to a liquefied gas regeneration system,

More particularly, the present invention relates to a liquefied gas regeneration system and a method for operating the liquefied gas regeneration system, and more particularly, to a system and method for regenerating liquefied gas, The present invention relates to a liquefied gas regeneration system and a method for operating the same.

Generally, natural gas is made in the form of Liquefied Natural Gas (LNG) liquefied at the cryogenic temperature at the place of production, and then transported over a long distance to the destination by an LNG carrier. LNG is obtained by cooling natural gas to a cryogenic temperature of about -163 ° C at normal pressure, and its volume is reduced to about 1/600 of that of natural gas, making it well suited for long distance transportation through the sea.

The LNG carriers are intended to be loaded with LNG and to be loaded into LNG storage tanks. The LNG carriers are equipped with LNG storage tanks capable of withstanding cryogenic LNG. Typically, these LNG carriers are unloaded to LNG storage terminals in a liquefied state as they are liquefied in the LNG storage tanks. The unloaded LNG is regenerated by the LNG regeneration facility installed in the land terminal and supplied to the consumer.

These LNG regasification facilities on land terminals are known to be economically advantageous when installed in a stable natural gas market because the natural gas market is well formed. However, it is economically disadvantageous to install LNG regeneration facilities on land terminals in the case of demanding natural gas demand seasonally, short-term or periodically limited due to high installation and operating costs.

Especially, when the LNG carrier is destroyed due to natural disasters, LNG carrier can not regenerate the LNG even if the LNG carrier arrives at the destination. have.

Accordingly, LNG regasification vessel (LNG regasification vessel) or floating LNG storage facility equipped with an LNG re-gasification system in an LNG carrier line is required to regenerate LNG from the sea and supply natural gas to the land terminal. A floating storage and regasification unit (FSRU) has been developed.

In LNG regasification vessels or floating LNG storage and regeneration facilities, LNG in the LNG storage tank is supplied to the vaporizer and vaporized. The LNG in the LNG storage tank is supplied to the vaporizer using a high-pressure pump.

The high-pressure pump includes a cylindrical housing, an LNG suction line for sucking the LNG by the high-pressure pump is connected to the lower side of the housing, and an LNG discharge line for discharging the LNG by the carburetor is connected to the upper portion of the housing. The housing is provided with a pumping chamber for pumping up the LNG to a high pressure, and components such as a motor and an impeller are installed in the pumping chamber. The rotating shaft of the motor is directed downward of the pumping chamber, and the impeller is integrally provided on the lower side of the rotating shaft of the motor. The impeller acts to pump the LNG sucked into the housing from the LNG storage tank through the LNG suction line to the high pressure. The LNG pumped by the impeller at high pressure is discharged to the carburetor through the LNG discharge line at the top of the housing.

However, in the high-pressure pump having such a configuration, the LNG vaporizes in the housing due to the heat of the motor and external heat input, and evaporation gas is generated. If the evaporation gas generated in the high-pressure pump is not discharged smoothly, the pressure in the high-pressure pump rises and LNG does not flow into the high-pressure pump, and the LNG level in the high-pressure pump is rapidly lowered, The pump trip which stops the operation of the high-pressure pump occurs, and it becomes impossible to supply the natural gas at the flow rate necessary for the gas demanding place.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a high-pressure pump which is capable of discharging evaporation gas So that the liquefied gas can be effectively treated when the liquefied gas overflows.

According to an aspect of the present invention, there is provided a high pressure pump for compressing liquefied gas supplied from a liquefied gas storage tank to a high pressure; A knock-out drum for receiving the evaporative gas generated from the high-pressure pump and maintaining the high-pressure pump at a minimum operable level; A gas discharge line for discharging gas from the knock-out drum; And a liquid discharge line for discharging the liquid from the knock-out drum, wherein gas discharged through the gas discharge line is supplied to a gas consumer including the liquefied gas storage tank or the fuel supply system, and the liquid discharge line Is supplied to a liquid consumer including the lower portion of the liquefied gas storage tank.

A supply pump for sucking and discharging the liquefied gas stored in the liquefied gas storage tank; And a suction drum for sucking the liquefied gas sucked by the supply pump before supplying the liquefied gas to the high pressure pump, wherein the liquefied gas contained in the suction drum is sucked by the pressure difference with the high- Can be supplied to the high-pressure pump from the drum.

Preferably, a vaporizer for supplying and vaporizing the liquefied gas compressed by the high-pressure pump; And a gas supply source supplied with the gas vaporized in the vaporizer.

Preferably, the second level control line discharges evaporated gas vaporized in the high-pressure pump and liquefied gas overflowed in the high-pressure pump from the high-pressure pump to the knock-out drum; And a second valve for controlling opening and closing and flow rate of the second level control line.

According to another aspect of the present invention, there is provided a liquefied gas storage tank for storing liquefied gas in a liquefied gas storage tank, temporarily storing the liquefied gas in a first drum, introducing liquefied gas stored in the first drum into a high- Characterized in that the evaporation gas vaporized in the pump is discharged to the second drum and the evaporation gas is discharged from the second drum to supply it as fuel or re-supply it to the liquefied gas storage tank / RTI >

Preferably, in the second drum, the liquefied gas overflowed from the high-pressure pump to the second drum is gas-liquid separated, and the separated liquid is supplied again to the lower portion of the liquefied gas storage tank.

Preferably, the liquefied gas is introduced from the first drum to the high-pressure pump by the head of the first drum, and when the level of the high-pressure pump is lower than the set value, The evaporation gas can be discharged.

According to the present invention, the evaporation gas in the high-pressure pump can be smoothly discharged, and the minimum operable level of the high-pressure pump can be maintained.

Further, the evaporated gas discharged from the high-pressure pump can be recovered without waste, effectively utilized, and the liquefied gas in a liquid state overflowed together with the evaporated gas can be separated and the separated liquefied gas can be recovered.

1 is a block diagram that schematically illustrates a liquefied gas regeneration system in accordance with one embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objects attained by the practice of the present invention, reference should be made to the accompanying drawings, which illustrate preferred embodiments of the present invention, and to the contents of the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout. The same elements are denoted by the same reference numerals even though they are shown in different drawings. In addition, the following examples can be modified in various forms, and the scope of the present invention is not limited to the following examples.

1 is a block diagram that schematically illustrates a liquefied gas regeneration system in accordance with one embodiment of the present invention. Hereinafter, a liquefied gas regeneration system and an operation method according to an embodiment of the present invention will be described with reference to FIG.

First, the liquefied gas is referred to as liquefied natural gas (hereinafter referred to as LNG) in the present specification. The liquefied gas may be liquefied from a ship or an offshore structure such as LNG RV or FSRU to a demand for gas such as on- But the present invention is not limited thereto.

The first to seventh valves, the supply pump, and the like to be described later may be controlled by a control unit (not shown), or may be set to be automatically controlled according to a set value.

1, according to an embodiment of the present invention, an LNG storage tank 100 for storing a liquefied gas such as LNG, an LNG storage tank 100 for regenerating LNG, (Not shown).

As shown in FIG. 1, the present invention is provided to increase the pressure of LNG to a high pressure by a vaporizer 400, and a component such as a motor and an impeller is provided in a vertical cylindrical housing. And a high-pressure pump 300 for increasing the pressure of the LNG to be pumped and discharged. In order for the high-pressure pump 300 to operate normally, the LNG must be maintained at a certain level or higher in the housing. The LNG introduced into the high-pressure pump 300 is vaporized by operation of a motor, impeller, The vaporized evaporated gas is filled in the upper portion of the housing by the density difference, and is discharged to the outside along the first evaporated gas discharge line (GL1).

The LNG stored in the LNG storage tank 100 is sucked by the supply pump 110 and supplied to the high pressure pump 300 along the first liquefied gas supply line LL1 and the second liquefied gas supply line LL2, The LNG boosted by the pump 300 is supplied to the vaporizer 400 along the third liquefied gas supply line LL3.

1, the supply pump 110 may be an underwater pump provided in the LNG storage tank 100, and the LNG sucked by the supply pump 110 may be supplied to the first liquefied gas supply line LL1, And a first drum 200 for temporarily storing the toner before supplying the toner to the developing roller 300. The first drum 200 may be a suction drum.

The LNG supplied from the suction drum 200 to the high pressure pump 300 is conveyed by the pressure difference between the suction drum 200 and the high pressure pump 300 or by the head of the suction drum 200, 200) is positioned above the high-pressure pump (300).

The first liquefied gas supply line LL1 may be provided with a first valve V1 for controlling the flow rate of the LNG supplied to the suction drum 200. The LNG accommodated in the suction drum 200 may be connected to the high pressure pump 300, A second valve V2 for controlling the flow rate of the LNG supplied from the suction drum 200 to the high pressure pump 300 may be provided in the second liquefied gas supply line LL2.

The second valve (V2) can be adjusted to open and close according to the LNG level (water level) of the suction drum (300). That is, when the LNG level in the suction drum 300 is equal to or greater than a preset value, the degree of opening can be increased so that the LNG flows from the suction drum 300 to the high-pressure pump 300.

Although not shown in the drawing, the second valve V2 may be controlled for redundancy by providing one or more valves of the same size in parallel.

The LNG boosted by the high pressure pump 300 is supplied to the vaporizer 400 along the third liquefied gas supply line LL3 and is boosted to the third liquefied gas supply line LL3 by the high pressure pump 300, A third valve V3 for controlling the flow rate of the LNG to be discharged through the second valve V3 may be provided.

As described above, in the high-pressure pump 300, the LNG is vaporized to generate an evaporation gas, and the generated evaporation gas is supplied to the first evaporation gas discharge line GL1 for discharging the evaporation gas in the high-pressure pump 300 Is stored in the high-pressure pump (300) before opening to increase the pressure in the high-pressure pump (300). When the pressure in the high-pressure pump 300 is increased by the evaporation gas, the LNG can not be transferred from the suction drum 200 to the high-pressure pump 300 only by the head of the suction drum 200, Accordingly, the LNG level in the high-pressure pump 300 is rapidly lowered to cause a trip, so that the LNG level can not be normally operated.

Particularly, when a cool-down of the LNG storage tank 100 or an initial start-up of the regeneration system is performed, a large amount of evaporation gas is generated and the high-pressure pump 300 so that the evaporation gas in the high-pressure pump 300 must be discharged smoothly in order to maintain the minimum operable level in the high-pressure pump 300.

According to an embodiment of the present invention, a first evaporation gas discharge line GL1 for discharging evaporation gas in the high pressure pump 300 and a second drum 500 for accommodating the evaporation gas discharged from the high pressure pump 300 So that the high pressure pump 300 can be maintained at the minimum operable level by discharging the evaporated gas in the high pressure pump 300 as necessary.

The minimum operating level of the high-pressure pump means the minimum level of the LNG to be pumped into the housing of the high-pressure pump 300 that enables the high-pressure pump 300 to operate normally without tripping or cavitation, May be preset by the operator or may be set at the designing or manufacturing stage of the high-pressure pump 300. [

A fourth valve V4 is provided in the first evaporation gas discharge line GL1 to control whether the evaporation gas is discharged from the high pressure pump 300 and to control the flow of the fluid flowing along the first evaporation gas discharge line GL1 The flow rate can also be adjusted.

The opening and closing of the fourth valve V4 can be controlled by measuring the pressure or the water level in the high pressure pump 300 or the pressure or the water level of the first drum 200. For example, The fourth valve V4 is opened so that the evaporation gas is discharged along the first evaporation gas discharge line GL1 or when the LNG level of the first drum 200 is lower than the set value, (V4) is opened to allow the evaporated gas in the high-pressure pump 300 to be discharged along the first evaporated gas discharge line (GL1).

In particular, according to the present invention, the evaporation gas discharged from the high-pressure pump 300 along the first evaporation gas discharge line GL1 is accommodated in the second drum 500, and is provided in the upper portion of the second drum 500, (FGSS) 600 or the third evaporative gas discharge line GL3 along a second gas discharge line GL2 for discharging the gas of the first gas discharge line GL2, The liquefied gas storage tank 100, and the like.

The fuel supply system 600 includes a pressure regulating means or a temperature regulating means for regulating the gas evaporated gas separated from the knock-out drum 500 to a fuel consumer, for example, a ship's engine, Fuel condition. The fifth valve V5 may be provided in the second evaporation gas discharge line GL2 and the flow rate of the evaporation gas flowing along the second evaporation gas discharge line GL2 may be controlled by controlling the fifth valve V5 have.

The third evaporative gas discharge line GL3 is connected to the upper portion of the LNG storage tank 100 from the upper portion of the knockout drum 500 to discharge the evaporated gas separated from the knockout drum 500 to the LNG storage tank 100 . The third evaporation gas discharge line GL3 can be used as an internal pressure regulating means of the LNG storage tank 100 and can be opened and closed by the sixth valve V6 provided in the third evaporation gas discharge line GL3 So that the flow rate of the evaporation gas flowing along the third evaporative gas discharge line GL3 can be adjusted.

In the first evaporative gas discharge line GL1 described above, when a large amount of evaporated gas is discharged from the high-pressure pump 300, the LNG in the high-pressure pump 300 overflows, The second drum 500 may be provided with a knock-out drum that receives the gas-liquid mixture and separates the gas-liquid mixture.

When the system is normally operated, if the liquefied gas does not overflow into the first evaporative gas discharge line (GL1) but overflows in an abnormal state, if the gas supplied to the gas consumer contains liquid, it may adversely affect the compressor So that the liquid can be separated from the second drum 500.

According to an embodiment of the present invention, the gas-liquid mixture containing the evaporation gas or the evaporation gas discharged from the high-pressure pump 300 along the first evaporation gas discharge line GL1 is supplied to the knock-out drum 500 , The gaseous vaporized gas is supplied to the gas consumer along the gas discharge line GL2 provided at the upper part of the knockout drum 500 and is supplied to the gas-liquid consuming region when gas-liquid mixture is supplied, condensate may be supplied to the liquid consumer along the liquid discharge line LL4 provided at the lower portion of the knockout drum 500. [

The liquid demanding means may be an LNG storage tank 100 and the liquid discharge line LL4 may extend from the lower portion of the knockout drum 500 to the lower portion of the inside of the LNG storage tank 100, So that the separated LNG can be recovered. Further, a seventh valve V7 is provided in the liquid discharge line LL4 to control the flow of the fluid flowing along the liquid discharge line LL4.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or scope of the invention as defined in the appended claims. . Therefore, the above-described embodiments are to be considered as illustrative rather than restrictive, and thus the present invention is not limited to the above description, but may be modified within the scope of the appended claims and equivalents thereof.

100: Liquefied gas storage tank
110: Feed pump
200: first drum
300: High pressure pump
400: vaporizer
500: second drum

Claims (7)

A high pressure pump for compressing the liquefied gas supplied from the liquefied gas storage tank to a high pressure;
A knock-out drum for receiving the evaporative gas generated from the high-pressure pump and maintaining the high-pressure pump at a minimum operable level;
A gas discharge line for discharging gas from the knock-out drum; And
And a liquid discharge line for discharging liquid from the knock-out drum,
The gas discharged through the gas discharge line is supplied to the gas demanding place including the liquefied gas storage tank or the fuel supply system,
And the liquid discharged through the liquid discharge line is supplied to a liquid consumer including the lower portion of the liquefied gas storage tank. The method according to claim 1,
A supply pump for sucking and discharging the liquefied gas stored in the liquefied gas storage tank; And
And a suction drum for accommodating the liquefied gas sucked by the supply pump before supplying the liquefied gas to the high-pressure pump,
And the liquefied gas contained in the suction drum is supplied from the suction drum to the high-pressure pump by a pressure difference with the high-pressure pump. The method of claim 2,
A vaporizer for supplying and vaporizing the liquefied gas compressed by the high-pressure pump; And
And a gas supply source supplied with the gas vaporized in the vaporizer. 4. The method according to any one of claims 1 to 3,
A second level control line for discharging evaporated gas vaporized in the high pressure pump and liquefied gas overflowed in the high pressure pump from the high pressure pump to the knockout drum; And
And a second valve for regulating opening and closing and flow rate of the second level control line. The liquefied gas is sucked in the liquefied gas storage tank and temporarily stored in the first drum,
The liquefied gas stored in the first drum is introduced into the high-pressure pump,
The evaporated gas vaporized in the high-pressure pump is discharged to the second drum,
And discharging the evaporation gas from the second drum to supply it as fuel or re-supply it to the liquefied gas storage tank. The method of claim 5,
In the second drum, the liquefied gas overflowed from the high-pressure pump to the second drum is gas-liquid separated,
And the separated liquid is re-supplied to the lower portion of the liquefied gas storage tank. The method of claim 6,
The liquefied gas is introduced into the high-pressure pump from the first drum by the head of the first drum,
And discharging the evaporated gas from the high-pressure pump to the second drum when the level of the high-pressure pump is lower than the set value.

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